Nanostructured tin dioxide – a promising multipurpose support material for catalytic and biocatalytic applications

• Nanostructured SnO2 powders with different particle and pore sizes were synthesized.
• 1 wt.% Pd or Pt-modifications substantially increased ethyl acetate total oxidation ability.
• Three lipases were effectively adsorbed on nanosized SnO2 with higher surface area.
• SnO2 enhanced activity and stability in multiple reaction cycles of the biocatalysts.

Nanostructured tin dioxide materials (nano-SnO2-A and nano-SnO2-B) were prepared using various tin precursors. They possess high specific surface areas due to their particle sizes and pore size distributions in the nanoscale. These materials were used as supports for lipases and for the preparation of nanocomposite catalysts that can be utilized in various environmentally beneficial processes. The obtained Pd- or Pt-containing catalysts were studied in the total oxidation of ethyl acetate reaction. The results showed that only a small amount (1 wt.%) of highly and homogeneously dispersed Pd or Pt additive is sufficient to improve and substantially decrease the temperature (with about 100 K) of total oxidation ability of the initial nanostructured SnO2 materials, which makes them very promising catalysts for elimination of volatile organic compounds. The material with the higher specific surface area (170 m2/g), nano-SnO2-A, was used as support for lipases from Candida rugosa, porcine pancreas and Rhizopus delemar (resp., nano-SnO2-A-CRL, nano-SnO2-A-PPL, nano-SnO2-A-RhDL). Nano-SnO2-A-RhDL exhibited up to 150-fold higher specific activity than the same enzyme adsorbed on silica. The synthetic activity and stability of the three biocatalysts were evaluated in multiple runs of synthesis of the banana flavor ester, an aroma widely used in food, pharmaceutical and detergent industries.

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